Automated media storage libraries are known for providing cost effective access to large quantities of stored information. Generally, media storage libraries include a large number of storage slots in which are stored portable data storage media. The typical portable data storage media is a tape cartridge, an optical cartridge, a disk cartridge, electronic storage media, and the like. By electronic storage media, Applicants mean a device such as a PROM, EPROM, EEPROM, Flash PROM, and the like.
One (or more) accessors typically accesses the data storage media from the storage slots and delivers the accessed media to a data storage device for reading and/or writing data on the accessed media. Suitable electronics operate the accessor(s) and operate the data storage device(s) to provide information to, and/or to receive information from, an attached on-line host computer system.
In a conventional automated media storage library, the storage slots are arranged in a planar orthogonal arrangement forming a “wall” of storage slots for holding data storage media. The plane may be a flat plane, or may be a cylindrical plane. To double the storage capacity, two “walls” of storage slots may be provided on either side of the accessor.
A number of different companies manufacture automated media storage libraries today, each model displaying various different features. One example is the IBM 3494 Tape Library Data Server. Some of the automated media storage libraries have dual or multiple accessors to provide a level of redundancy and to enhance performance.
In operation, one or more host computers provide requests to the data storage and retrieval system to mount one or more information storage media in one or more data storage devices disposed therein. On occasion, however, the requesting host computer does not specify which one or more physical/logical volumes comprise the designated media. Rather, the host specifies a category of media. Such a host request is sometimes called a “category mount”.
In response to such a category mount, the data storage and retrieval system queries its database using the categorical information supplied by the requesting host computer to identify the physical/logical volume(s) wherein the requested information is stored. During normal operation, volumes are moved from category to category. Over time this causes database fragmentation resulting in slower database performance.
Optimal database performance is desirable due to the number of volumes typically stored in the library, and due to the round-the-clock use, i.e. “24/7” operation, of the data storage and retrieval system. Prior art database maintenance methods require human intervention to monitor database performance and to undertake database maintenance. In addition, prior art database maintenance methods do not include performing unscheduled maintenance.